On the Dark Matter Profile Mass Dependence

Astronomy Reports - In this paper, we check the claim of dependence of the halo density profile on the ratio between stellar and halo mass. Namely, we want to continue the work done in a previous...     

暗物质暗能量与地球动力学

近年来世界重大科技进展中,"暗物质"与"暗能量"始终是关注的焦点。暗物质无法用肉眼看见,意味着它们不能发射电磁波,只能通过引力产生的效应知道它的存在。暗能量是一种不可见的、充溢空间、具有负压强的能量。这种负压强在长距离类似于一种反引力。宇宙中所有的恒星和行星的运动都是由暗能量与万有引力来推动的。但是虽然天体物理对暗物质与暗能量的研究有长足进步,并且尽管它与地球科学密切相关,但是在国内地学界对这个问题却少人顾及。本文引用、抄录、梳理已有暗物质与暗能量文献,对暗物质与暗能量作一初略的介绍,并试图以此观点出发,对地球演化中动力学问题进行探讨。我们认为,地球内的暗能量是推动地球构造演化的主要原动力,它对地球演化的主要效应是使地球膨胀。地球的膨胀引发了其他许多地质作用和效应。文中以青藏高原、秦岭造山带及东南亚西太平洋为例,说明在地球物理研究中都未发现其俯冲的迹象,它们应是暗能量驱动地球膨胀造成的造山带。     

Galactic Constraints on Fermionic Dark Matter

In order to explain Galactic structures, a self-gravitating system composed of massive fermions in spherical symmetry is considered. The finite mass distribution of such a component is obtained after solving the Einstein equation for a thermal and semi-degenerate fermionic gas, described by a perfect fluid in hydrostatic equilibrium and exposed to cutoff effects (e.g. evaporation). Within this more general approach a family of density profiles arises, which explains dark matter halo constraints of the Galaxy and provides at the same time an alternative to the central black hole scenario in Sgr A*. This analysis narrows the allowed particle mass to mc² = 48?345 keV.     

Stellar-to-Halo Mass Ratio and Dark Matter Profiles

Astronomy Reports - This paper seeks to verify if the inner halo density profile depends on the ratio between stellar and halo mass. The work follows the previous one by Del Popolo and Pace (2016),...     

Self Interactions in Warm Dark Matter: A View from Cosmological Perturbation Theory

Astronomy Reports - We provide a short overview into Self Interacting Warm Dark Matter (SI-WDM) models from the context of Cosmological Perturbation Theory (CPT). The aim is to generalize...     

Angular Momentum Distribution in Galaxies and Inner Haloes Profile

We study the problem of the determination of a high precision cosmological mass function, which is of fundamental importance in several problems of astrophysics, like the building up of an halo model. The determination of a mass function through numerical simulation is time demanding, and restrict to particular cosmological parameters. Analytical methods, allow to determine high precision mass functions, without the limitations of the simulations. We improve on previous analytical models, reaching high level of precision. In particular, we improve the scheme of Del Popolo presented in older and more recent papers, based on the excursion set approach. We further improve the mass function with respect to the quoted papers, using an higher order first crossing distribution, and an improved barrier with respect previous papers. As a result, we can obtain a mass function with a precision of 1%, in the mass range ≃ (10⁹−10¹⁵) h⁻¹M☉, and in the redshift range 0 < z s< 10. The paper also shows how the use of the quoted improved first-crossing distribution, improves the agreement between the conditional mass function, and simulations.

     

月球风暴洋火山口暗物质矿物反演及地质意义

月表主要矿物的空间分布是研究月球起源及演化等科学问题的重要信息之一.以风暴洋地区为例, 根据不同矿物光谱在可见光-近红外波段的吸收特征, 使用印度M3(moon mineralogy mapper)数据, 应用波谱特征拟合法(SFF)反演了火山口附近暗物质区域的单斜辉石、斜方辉石、橄榄石和尖晶石等铁镁质矿物的分布, 反演结果显示: 风暴洋地区提取的铁镁质矿物分布较集中, 其中辉石含量较多, 橄榄石和尖晶石含量相对较少.另外着重分析了橄榄石、尖晶石与周围矿物的关系及其地质意义.将提取结果与Lucey用于Clementine影像的光学模型填图结果进行对比显示, 提取的橄榄石分布集中, 但不存在大尺度的分布, 这与本文的研究区域面积有关; 就位置而言, 二者具有较好的一致性.      

泡沫固井水泥浆密度与环空液柱压力变化规律研究

超低密度泡沫水泥浆是解决低漏失压力井固井漏失,提高固井质量的有效措施。除泡沫水泥浆体系的开发与性能优化外,掌握泡沫水泥浆在环空内产生的静液柱压力随井深的变化规律,是成功实施该工艺技术的前提。借助实际气体状态方程,考虑温度、压力变化对充入氮气的影响,建立了静液柱压力和水泥浆密度与井深之间的数学模型,以迭代法编程求解该隐函数方程,并借助VB语言实现程序运算。分析了含气量变化、井深等因素对泡沫水泥浆密度及静液柱压力的影响规律,并提出了泡沫水泥浆“防漏”与“压稳”固井浆柱结构设计思路,为该工艺平衡压力固井设计提供了一定的参考和理论依据。该设计方法经现场应用,证实其运算结果的可靠性。     

Dark energy in flows of galaxies

It has traditionally been taken for granted that Hubble’s law is the key relation in cosmology, while it is surprisingly mysterious on the local scales of 1–30 Mpc where it was originally discovered. The progress in observational cosmology and, in particular, the discovery of dark energy have changed the views, and now we see that Hubble’s law works hardly at truly cosmological distances, but it rules very well on local scales. Recent observations with the HST, in combination with a theory model of the local expansion flows, give a clear evidence to the presence of dark energy in the local universe. It is dark energy that dominates the dynamics of the local flows and introduces to them the approximately linear velocity-distance relation with nearly universal expansion time-rate.     

On the Relationship between Refractive Index and Density for SiO2-polymorphs

Five different refraction formulas were applied to SiO₂ polymorphs in order to determine the most suitable refractive index-density relation. 13 SiO₂ polymorphs with topological different tetrahedral frameworks are used in this study including eight new low density SiO₂ polymorphs — so called “guest free porosils”. These SiO₂ polymorphs cover a density range from 1.76 to 2.92 g/cm³. The mean refractive indices (ovn) of the porosils have been determined by the immersion method, the densities (ρ) were calculated from the unit cell parameters. Assuming the polarizability (α) of all SiO₂ polymorphs to be constant the general refractivity formula $$\{ 2\overline {11} 0\} \langle 0001\rangle $$ turned out to be the most suitable for SiO₂ polymorphs. Regression analysis yields an electronic overlap parameter b=1.2(1).     

Dark energy in the three-body problem: Wide triple galaxies

The structure and evolution of triple galaxy systems in the presence of the cosmic dark-energy background is studied in the framework of the three-body problem. The dynamics of wide triple systems are determinedmainly by the competition between the mutual gravitational forces between the three bodies and the anti-gravity created by the dark-energy background. This problem can be solved via numerical integration of the equations of motion with initial conditions that admit various types of evolutionary behavior of the system. Such dynamical models show that the anti-gravity created by dark energy makes a triple system less tightly bound, thereby facilitating its decay, with a subsequent transition to motion of the bodies away from each other in an accelerating regime with a linear Hubble-law dependence of the velocity on distance. The coefficient of proportionality between the velocity and distance in this asymptotic relation corresponds to the universal value H_Λ = 61 km s^?1 Mpc^?1, which depends only on the dark-energy density. The similarity of this relation to the large-scale recession of galaxies indicates that double and triple galaxies represent elementary dynamical cells realizing the overall behavior of a system dominated by dark energy on their own scale, independent of their masses and dimensions.     

广州感潮河段底泥有机质特征

珠江广州河段水文水质特征受感潮作用影响很大，因感潮上溯作用，靠近市区河段的严重污染，不仅对下游水质造成影响，而且对上游珠江西航道和流溪河这一重要水源区的水质有影响。本研究分析了广州上游珠江西航道和流溪河这一河段底泥中有机质特征，从有机地球化学角度探讨感潮作用对广州市上游水质的影响范围和程度，指明鸦岗以上河段受感潮作用影响很小，而西村和石门则受较大程度影响，有机质呈明显人为污染特征。本研究同时表明有机地球化学原理方法可以应用于探讨河流水文水质。     

"Dark Ages"冷事件研究进展

以历史文献资料、树木年轮、冰芯等记录为依据, 论证了"Dark Ages"(400～600 AD)时期发生过一次以冷干为特征的气候突变. 此次气候突变在中国及世界其它地区均有所反映, 可以推断此次气候突变在北半球比较明显甚至具有全球性, 它对人类社会的发展造成了灾难性的影响. 到目前为止关于"Dark Ages"时期气候突变的原因有许多争议, 有待于进一步的研究证实. 气候总是在冷暖波动中前进的, 结合紧随其后的中世纪暖期(MWP), 由"Dark Ages"向"MWP"的过渡可以为认识由小冰期(LIA)向20世纪全球变暖的转变提供借鉴.     

滇西马厂箐岩体暗色包体成因研究

滇西马厂箐岩体斑状花岗岩中发育大量暗色包体.对包体和寄主岩的主量、稀土、微量元素及Pb同位素进行分析.主量和微量元素研究表明,包体及寄主岩具有一定的成因联系.Pb同位素则反映两者可能分别起源于EMⅡ和下地壳.在此基础之上结合包体岩相学研究,认为暗色包体是岩浆混合作用的产物.暗色包体对于揭示富碱岩浆起源、深部作用过程以及其与成矿的关系等提供了可靠的地质依据,反映了马厂箐岩体可能是壳幔岩浆混合成因,幔源岩浆提供了成矿物质.     

Dark energy in the two-body problem: The local group of galaxies

The two-body problem of classical mechanics can be extended in a natural way by introducing a universal dark-energy background, which acts as a third dynamical factor. For real systems of galaxies, the corresponding additional acceleration is described by general relativity in the Newtonian limit, in which deviations from the Minkowski metric are very small. It is shown that this acceleration has the same form in different inertial and non-inertial reference frames. The invariance of the acceleration produced by dark energy reflects the fact that, according to its mechanical properties, dark energy is a vacuum that is comoving with any motion. In this generalized formulation, as in the classical case, the two-body problem with a dark-energy background reduces to the motion of a single body in a central field. Two problems of this kind are considered for the Local Group of galaxies. The first, “internal,” problem concerns the binary system formed by the main bodies of the Local Group: our galaxy and M31. The subject of the second, “external,” problem is the binary system formed by the Local Group as a whole and its closest neighbor, the Virgo Cluster. In the internal problem, the effect of the dark energy is that the binary system is not bound if its mass does not exceed 3 × 10¹² M_⊙, which is allowed by the observational data. The external problem demonstrates the possibility of an evolutionary scenario in which a group could initially be located in the volume of a cluster, but then leave it and, moving away with an acceleration created by dark energy, arrive at the observed distance from the cluster.     

构造叠加晕结合五方位测井在甘肃省贾公台金矿寻找深部矿体中的应用

贾公台金矿为甘肃党河南山地区规模最大的金矿床。为探索深部矿化、寻找盲矿体,在贾公台矿段开展原生晕研究,建立原生叠加晕轴向分带,发现贾公台金矿具反向分带特征。说明该矿体深部存在多期次成矿作用。结合地井五方位测井,预测深部3 200 m标高以下存在盲矿体。深部钻探发现了厚度大、品位高的多层金矿体,新增金资源量12吨,取得了显著找矿成果。构造叠加晕结合地井五方位测井成功圈定贾公台金矿深部矿体的实践,对同类矿床的深部找矿具有重要指导意义。     

振冲碎石桩在杂填土地基中的应用

介绍了某工程应用振冲碎石桩在堆积时间较短的杂填土地基中的处理情况,尤其是对承载力特征值要求较高的杂填土地基提出了经济、合理的处理方法。     

Dark matter and dark energy in dwarf galaxy systems

Quantitative estimates of themaximumallowed totalmasses and sizes of the dark-matter halos in groups and associations of dwarf galaxies—special types of metagalactic populations identified in recent astronomical observations with the Hubble Space Telescope—are presented. Dwarf-galaxy systems are formed of isolated dark-matter halos with a small number of dark galaxies embedded in them. Data on the sizes of these systems and the velocity dispersions of the embedded galaxies can be used to determine lower limits on the total dark-halo masses using the virial theorem. Upper limits follow from the conditions that the systems immersed in the cosmic dark-energy background be gravitationally bound. The median maximum masses are close to 10¹² M _⊙ for both groups and associations of dwarf galaxies, although the median virial masses for these two types of systems differ by approximately a factor of ten.     

陕西铧厂沟金矿床成矿物质来源探讨

对陕西铧厂沟金矿几个矿带不同矿石类型的稀土元素和铅同位素分析的结果发现,铧厂沟金矿的成矿物质主要来源于地壳深部或上地幔,部分矿段经历了多期次的热液叠加,铧厂沟金矿存在多个矿化浓集中心,其中刘家河坝矿段是成矿热液来源的主要中心。     

东南极达尔克冰川表面运动速度特征研究

2007-2012年,在东南极达尔克冰川实施了18期空间方向交会观测,解算得到了冰川的运动规律:其整体平均运动速度为0.41 m·d^-1,平均流向的方位角为7.01°;总的来说,其冬季和夏季的流速基本相当,但冰川前缘附近的运动在冬季显得更为活跃;冰川横截面上从边缘到中心,流速逐渐增大,流速最大的点出现在冰川中轴线上,流速最小的点则出现在边界附近;沿冰川流动方向,从上游至入海口,流速亦逐渐增大,冰川前缘流速最大,此处有较多的冰裂缝发育.与之前的遥感研究结果相比较,冰川运动比较稳定,流速未发现显著变化.